Cylindrical lithium secondary battery

Abstract

A cylindrical lithium secondary battery includes a positive electrode ( 1 ) having a positive electrode mixture layer disposed on a surface of a positive electrode current collector made of a conductive metal foil and containing a positive electrode active material, and a negative electrode ( 2 ) having a negative electrode mixture layer disposed on a surface of a negative electrode current collector made of a conductive metal foil and having a negative electrode active material containing silicon particles and/or silicon alloy particles. The amount of the positive electrode active material is 50 mg or less per 1 cm 2 of the positive electrode, the average particle size of the silicon particles and/or silicon alloy particles is from 5 μm to 15 μm, and the theoretical electrical capacity ratio of the negative electrode to the positive electrode is 1.2 or greater.

1 . A cylindrical lithium secondary battery comprising:
 a battery case;   a non-aqueous electrolyte; and   a spirally-wound electrode assembly accommodated in the battery case, the spirally-wound electrode assembly comprising a positive electrode, a negative electrode, and a separator interposed between the positive and negative electrodes, the positive electrode and the negative electrode being disposed facing each other across the separator,   the positive electrode having a positive electrode current collector made of a conductive metal foil and a positive electrode mixture layer disposed on a surface of the positive electrode current collector, the positive electrode mixture layer comprising a positive electrode binder and a positive electrode active material containing a layered lithium-transition metal composite oxide represented by the chemical formula Li a Ni b Co c Mn d Al e O 2  where 0≦a≦1.1, b+c+d+e=1, 0≦b≦1, 0≦c≦1, 0≦d≦1, and 0≦e≦0.1, wherein the amount of the positive electrode active material is 50 mg or less per 1 cm 2  of the positive electrode, and   the negative electrode having a negative electrode current collector made of a conductive metal foil and a negative electrode mixture layer disposed on a surface of the negative electrode current collector, the negative electrode mixture layer comprising a negative electrode binder and a negative electrode active material containing silicon particles and/or silicon alloy particles, wherein the average particle size of the silicon particles or the silicon alloy particles is from 5 μm to 15 μm, and   wherein the theoretical electrical capacity ratio of the negative electrode to the positive electrode is 1.2 or greater.   
   
   
       2 . The cylindrical lithium secondary battery according to  claim 1 , wherein the positive electrode contains Li 2 CO 3 , and the amount of the Li 2 CO 3  with respect to the total amount of the positive electrode active material is 0.2 mass % or greater. 
   
   
       3 . The cylindrical lithium secondary battery according to  claim 2 , wherein the Li 2 CO 3  exists on a surface of the positive electrode active material. 
   
   
       4 . The cylindrical lithium secondary battery according to  claim 1 , wherein the positive electrode active material contains a layered lithium-transition metal composite oxide represented by the chemical formula Li a Ni b Co c Al e O 2 , where 0≦a≦1.1, b+c+e=1, 0<b≦0.85, 0<c≦0.2, and 0≦e≦0.1. 
   
   
       5 . The cylindrical lithium secondary battery according to  claim 2 , wherein the positive electrode active material contains a layered lithium-transition metal composite oxide represented by the chemical formula Li a Ni b Co cf Al e O 2 , where 0≦a≦1.1, b+c+e=1, 0≦b<0.85, 0<c≦0.2, and 0≦e≦0.1. 
   
   
       6 . The cylindrical lithium secondary battery according to  claim 1 , wherein the separator is made of a microporous polyethylene film, and the microporous film has a penetration resistance of 350 g or greater and a porosity of 40% or greater. 
   
   
       7 . The cylindrical lithium secondary battery according to  claim 2 , wherein the separator is made of a microporous polyethylene film, and the microporous film has a penetration resistance of 350 g or greater and a porosity of 40% or greater. 
   
   
       8 . The cylindrical lithium secondary battery according to  claim 1 , wherein the silicon particles and the silicon alloy particles have a crystallite size of 100 nm or less. 
   
   
       9 . The cylindrical lithium secondary battery according to  claim 2 , wherein the silicon particles and the silicon alloy particles have a crystallite size of 100 nm or less. 
   
   
       10 . The cylindrical lithium secondary battery according to  claim 1 , wherein the silicon particles and the silicon alloy particles are prepared by thermally decomposing, or thermally reducing, a material containing a silane compound. 
   
   
       11 . The cylindrical lithium secondary battery according to  claim 2 , wherein the silicon particles and the silicon alloy particles are prepared by thermally decomposing, or thermally reducing, a material containing a silane compound. 
   
   
       12 . The cylindrical lithium secondary battery according to  claim 1 , wherein the silicon particles and the silicon alloy particles contain oxygen and, as an impurity, at least one element selected from the group consisting of phosphorus, boron, aluminum, iron, calcium, sodium, gallium, lithium, and indium. 
   
   
       13 . The cylindrical lithium secondary battery according to  claim 2 , wherein the silicon particles and the silicon alloy particles contain oxygen and, as an impurity, at least one element selected from the group consisting of phosphorus, boron, aluminum, iron, calcium, sodium, gallium, lithium, and indium. 
   
   
       14 . The cylindrical lithium secondary battery according to  claim 1 , wherein the negative electrode binder comprises a thermoplastic resin. 
   
   
       15 . The cylindrical lithium secondary battery according to  claim 2 , wherein the negative electrode binder comprises a thermoplastic resin. 
   
   
       16 . The cylindrical lithium secondary battery according to  claim 14 , wherein the thermoplastic resin comprises a polyimide resin. 
   
   
       17 . The cylindrical lithium secondary battery according to  claim 15 , wherein the thermoplastic resin comprises a polyimide resin. 
   
   
       18 . The cylindrical lithium secondary battery according to  claim 1 , wherein the negative electrode active material layer contains graphite powder. 
   
   
       19 . The cylindrical lithium secondary battery according to  claim 2 , wherein the negative electrode active material layer contains graphite powder. 
   
   
       20 . The cylindrical lithium secondary battery according to  claim 18 , wherein the average particle size of the graphite powder is from 3 μm to 15 μm, and the amount of the graphite powder with respect to the total amount of the negative electrode active material is from 3 mass % to 20 mass %. 
   
   
       21 . The cylindrical lithium secondary battery according to  claim 19 , wherein the average particle size of the graphite powder is from 3 μm to 15 μm, and the amount of the graphite powder with respect to the total amount of the negative electrode active material is from 3 mass % to 20 mass %. 
   
   
       22 . The cylindrical lithium secondary battery according to  claim 1 , wherein the non-aqueous electrolyte contains CO 2  and/or fluoroethylene carbonate. 
   
   
       23 . The cylindrical lithium secondary battery according to  claim 2 , wherein the non-aqueous electrolyte contains CO 2  and/or fluoroethylene carbonate. 
   
   
       24 . A method of manufacturing a cylindrical lithium secondary battery, comprising:
 applying a positive electrode mixture slurry containing a positive electrode binder and a positive electrode active material onto a surface of a positive electrode current collector made of a conductive metal foil so that the amount of the positive electrode active material is 50 mg or less per 1 cm 2  of the positive electrode, the positive electrode active material containing a layered lithium-transition metal composite oxide represented by the chemical formula Li a Ni b Co c Mn d Al e O 2  where 0≦a≦1.1, b+c+d+e=1, 0≦b≦1, 0≦c≦1, 0≦d≦1, and 0≦e≦0.1, to thereby prepare a positive electrode in which a positive electrode mixture layer is formed on the surface of the positive electrode current collector;   applying a negative electrode mixture slurry containing a negative electrode binder and a negative electrode active material containing silicon particles and/or silicon alloy particles having an average particle size of from 5 μm to 15 μm, onto a surface of a negative electrode current collector made of a conductive metal foil so that the theoretical electrical capacity ratio of the negative electrode to the positive electrode is 1.2 or greater, to thereby prepare a negative electrode in which a negative electrode mixture layer is formed on the surface of the negative electrode current collector; and   spirally winding the positive and negative electrodes with a separator interposed therebetween to prepare a spirally-wound electrode assembly, thereafter putting the spirally-wound electrode assembly into a battery case, and filling a non-aqueous electrolyte into the battery case.   
   
   
       25 . The method according to  claim 24 , wherein the silicon particles and the silicon alloy particles used are prepared by thermally decomposing, or thermally reducing, a material containing a silane compound.